Process and functional unit for the optimization of displaying progressively coded image data

ABSTRACT

In a process and unit for gradual decoding, archiving and graphic display of progressively decoded image data, time intervals between the time points of consecutive decoding steps, during which network users receive ever more refined image resolution when downloading image data from a central network server to the client computer using transferred and decoded partial data quantities ΔLi as preview images, are generated with abbreviated time spans that are optimized with respect to minimization of system usage by the decoding system. For this purpose, the receiving data rates for transfer of the individual partial data quantities, which are taken into account through improvements generated by the individual decoding steps of a quality metric showing the degree of image resolution and the temporary usage of the decoding system upon determination of the decoding time points. The wait times between the time points of directly consecutive decoding steps are calculated using statistical image quality parameters of received partial image data in such a manner that the decoding steps which do not lead to a perceptible improvement in the quality of a reconstructed image are suppressed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns a process and a unit for gradualprocessing and, when necessary, graphic display of progressively codedimage data, which help to shorten and, with respect to minimization ofsystem usage, optimize the time span during which network users areprovided progressively refined image resolution when graduallydownloading image data from a central network server to their localclient computers in the form of transferred and decoded partial dataquantities as preview images, for example.

2. Description of the Prior Art

The following provides a brief presentation of the principle ofprogressive image coding as applied within the framework of theProgressive JPEG Standard. Because the solution that forms the basis ofthe invention is, however, independent of the actual image codingstandard and only one progressive process is assumed, other standards,e.g. JPEG 2000 or Interlaced GIF, can be used besides the ProgressiveJPEG Standard described here.

The file format that has come to be known as “Progressive JPEG” is anexpansion of the graphic file format JPEG that can be used to graduallybuild and save a photographically realistic image in a Web browser. Inthis process, already downloaded partial data quantities AL _(i) [kByte]are decoded in several decoding steps simultaneously during downloadingof the data quantity to be transferred $\begin{matrix}{L_{total} = {\frac{1}{1.024}\frac{MByte}{kByte}{\sum\limits_{i = 1}^{N}{\Delta\quad{L_{i}\lbrack{MByte}\rbrack}}}}} & (1)\end{matrix}$of an image file from a central network server to the local clientcomputer of a network user so that ever more detailed preview imagesV_(i) of the graphic to be reconstructed can be displayed until thetotal image file has been downloaded from the network server. Theresolution of the graphic will become gradually ever finer during theloading process and the resulting picture will be sharper until thepredefined resolution RB is achieved through the quantization of theoriginal image. An advantage of this process is that a person viewing aWeb page with embedded graphic elements will get an initial visualimpression of the image file when the download begins and does not haveto wait until the complete image has been transferred. The goal is

-   -   to shorten the elapsing wait time for the graphic display of        useable j-th version of a preview image V_(i) for creating an        early visual impression of the downloaded image file        $\begin{matrix}        {{T_{W}(j)}{\text{:} = {\sum\limits_{i = 1}^{j}{\Delta\quad{t_{w,i}\lbrack s\rbrack}}}}} & \left( {2a} \right)        \end{matrix}$    -    so that the network user already at an early point in time ti        of the loading process can have valuable image information from        the data quantity transferred up to that point $\begin{matrix}        {{{{L_{ist}(j)}\text{:}} = {{\sum\limits_{i = 1}^{j}{\Delta\quad L_{i}}} = {{L_{gas} \cdot 1.024}\frac{kByte}{MByte}{\sum\limits_{i = 1}^{j}{\Delta\quad{l_{i}\lbrack{kByte}\rbrack}}}}}}{{{with}\quad j} = \left\{ {1,{2\quad\ldots}\quad,N} \right\}}} & \left( {2b} \right)        \end{matrix}$    -    made available whereby $\begin{matrix}        {\Delta\quad l_{i}\text{:}{= {{100 \cdot \frac{1}{1.024}}{\frac{MByte}{kByte} \cdot \frac{\Delta\quad l_{i}}{L_{gas}}}}}} & \left( {2c} \right)        \end{matrix}$    -    which designates the percentage increase of the partial data        quantity received and decoded in the decoding step D_(i).    -   to transparently display the progress of the image transfer        achieved at each decoding step D_(i) at the time points ti,        which shows an improvement of the image quality, and    -   controls the loading process interactively, if necessary, to        cancel or continue.

In order to achieve this, the images used with progressive JPEG aresplit up as in the baseline JPEG process in 8×8 blocks and aretransformed using the Discrete Cosinus Transformation (DCT). Accordingto the quantification, for which parameters may be set, each block willnot be coded immediately but will first be temporarily saved in a databuffer until all blocks contained in the image are quantified. Thebuffer content will then be coded in several steps. Therefore there isno sequential coding of the individual blocks as in the baseline JPEGprocess. The loading and decoding of partial data quantities for displayof rough preview images with gradually refined resolution proceedssignificantly faster then a line-by-line image composition forreconstructing the fine resolution of the original image.

The technical problem encountered in decoding in this context lies inthe optimal determination of the time distances of two immediatelyconsecutive decoding steps D_(i−1) and D_(i) that must be selected insuch a way that the mean data reception rate R, the improvements inimage quality Q achieved in the individual coding steps and theavailable performance capacity and the relative load (burden)$\begin{matrix}{\rho = {{100 \cdot \frac{T_{D}}{T_{W}}} = {100 \cdot {\frac{\sum\limits_{i = 1}^{N}{\Delta\quad t_{D,i}}}{\sum\limits_{i = 1}^{N}{\Delta\quad t_{W,i}}}\quad\lbrack\%\rbrack}}}} & \left( {3a} \right)\end{matrix}$of the applied decoding and display system can be taken into account. Inthis instance, $\begin{matrix}{{T_{W}\text{:}} = {{\sum\limits_{i = 1}^{N}{\Delta\quad t_{W,1}}} = {t_{N} - {t_{0}\quad\lbrack s\rbrack}}}} & \left( {3b} \right)\end{matrix}$designates the total required wait time from the beginning of thedownload process to the time t_(o)=0 s until the display of the finalversion V_(n) of maximum resolution R_(B) of an image at time t_(N) and$\begin{matrix}{T_{D}{\text{:} = {\sum\limits_{i = 1}^{N}{\Delta\quad{t_{D,i}\quad\lbrack s\rbrack}}}}} & \left( {3c} \right)\end{matrix}$is the total required time span for decoding and graphic visualizationof this final version V_(N), whereby $\begin{matrix}{t_{D}\overset{1}{\leq}T_{W}} & \left( {3d} \right)\end{matrix}$must be valid; Δt _(w,i) is the wait time between both decoding steps D_(i−1) and D_(i), Δt _(D,i) is the actual required computation time fordecoding and graphic visualization of the partial data quantity ΔL_(i)and $\begin{matrix}{\rho_{i} = {100 \cdot {\frac{\Delta\quad t_{D,i}}{\Delta\quad t_{W,i}}\quad\left\lbrack \% \right\}}}} & \left( {3e} \right)\end{matrix}$the usage of the decoding and display system at the time interval Δt_(w,i) which may not be greater than 100%. The following must also apply$\begin{matrix}{{\Delta\quad t_{D,i}}\overset{1}{\leq}{\Delta\quad t_{W,i}\quad{\forall{i.}}}} & \left( {3f} \right)\end{matrix}$Conventional processes used in the current state of technology usualdetermine the time durations Δt_(D,l) between the time points t_(i−1)and t_(i) of sequential decoding steps D_(i−1) and D _(i) eitherindependently from the received data quantity List (j) (Version 1), thedecoding steps are implemented at regular time distances Δt _(D)(Version 2) or use a combination of both processes (Version 3). As isexplained in the following, these methods run into technologicallyconditioned limits.

When executing version 1, a procedure executed to determine the timedistancesΔt _(D,i) ≡Δt _(W,i) :=t _(i) −t _(i−1) ≠const.[s] (for iε[1,2, . . . ,N}  (4)of sequential decoding processes D_(i−1) and D_(i) starts the i-thdecoding (D_(i)) and display step (V _(i) ), when an established, butvariable, data quantity ΔL_(i) of progressively coded image data isavailable to the decoding and display system. So, as an example, thefirst decoding step D_(i) is executed after the first block B₁ ofprogressively coded image data is received by the decoding system. Thepartial data quantity ΔL₁ of the first block B₁ is thereby an optionalsystem parameter. Further decoding steps D₂ through D_(n) areimplemented after further blocks B₂ thru B_(n), whose sizes ΔL₂ throughΔL_(n) depend respectively on the sizes ΔL ¹ through ΔL_(N−1) for thepreviously received blocks B₁ through B_(n−1) and their systemparameters are determined suitable, were received by the decodingsystem. Such a determination of the decoding distances Δt_(p,l) takesinto account the mean transfer rate $\begin{matrix}{R = {{8{\frac{Bit}{Byte} \cdot \frac{L_{ges}}{T_{W}}}}\quad = {8{\frac{Bit}{Byte} \cdot \frac{1}{1.024}}{\frac{Mbyte}{kByte} \cdot \frac{1}{T_{W}} \cdot {\sum\limits_{i = 1}^{N}{\Delta\quad{L_{i}\quad\left\lbrack {{Mbit}\text{/}s} \right\rbrack}}}}}}} & (5)\end{matrix}$the total data quantity received L_(total)s during the time T_(w) onlyindirectly via the system parameters Δ_(Li). Then there is a slowreception of the data at long wait times Δt _(w,l) between the decodingsteps D_(i−1) and D_(i), whereas there is a fast reception of data atvery short wait times Δt_(w,i). In the latter case, the decodingprocesses can no longer be executed in a timely manner due to thelimited performance capacity of the decoding system is somecircumstances. In order to avoid this, in many systems the instant value$\begin{matrix}{{R_{i} = {8{\frac{Bit}{Byte} \cdot \frac{1}{1.024}}{\frac{MByte}{kByte} \cdot \frac{\Delta\quad L_{i}}{\Delta\quad t_{D,i}}}}}\left( {{{for}\quad i} \in \left( {1,{2\quad\ldots},N} \right)} \right.} & (6)\end{matrix}$of the data rate R of received image data form a system parameter thatis either regularly measured or is recognized as an estimate by thedecoding system.

If, as in version 2, the display steps V_(i) are executed in regular,constant time intervals Δt _(p) , the total image data quantity receivedat the time t_(j) of display by the decoding and display system$\begin{matrix}\begin{matrix}{{L_{ist}^{\prime}(j)}:={{{j \cdot \Delta}\quad L} = {1.024\quad{\frac{k\quad{Byte}}{MByte} \cdot j \cdot L_{ges} \cdot \Delta}\quad{l\quad\left\lbrack {k\quad{Byte}} \right\rbrack}}}} \\{\left( {{{with}\quad j} \in \left\{ {1,2,\ldots\quad,N} \right\}} \right),}\end{matrix} & \left( {7a} \right)\end{matrix}$whereby $\begin{matrix}{{\Delta\quad l}:={{100 \cdot \frac{1}{1.024}}\quad{\frac{MByte}{k\quad{Byte}} \cdot {\frac{\Delta\quad L}{L_{ges}}\quad\lbrack\%\rbrack}}}} & \left( {7b} \right)\end{matrix}$  with ΔL₁=ΔL₂= . . . ΔL_(i)= . . . ΔL_(N)=:ΔL[kByte]  (7c)the increase as a percentage of the received data and designated in theindividual decoding steps as decoded constant partial data quantitiesΔL, will be decoded and graphically visualized. The time intervalst _(D,i) :=t _(i) −t _(i)−1=const.[s] (for iε{1,2, . . . , N})  (8a)between two consecutive decoding steps D_(i−1) and D _(i) , wherebyΔt_(D,1)=Δt_(D,2)= . . . Δt_(D,i)= . . . Δt_(D,N)=:Δt_(D)[s] andΔt_(D,1)≦Δt_(W,1)  (8b)is valid, form a system parameter of the decoding system and also takeinto account the performance capacity of the decoding system. In thecase of such a manner of proceeding, the data rate $\begin{matrix}\begin{matrix}{R_{I} = {8{\frac{Bit}{Byte} \cdot \frac{1}{1.024}}\quad{\frac{M\quad{Byte}}{k\quad{Byte}} \cdot \frac{\Delta\quad L_{i}}{\Delta\quad t_{W,i}}}}} \\{\quad{= {{8{\frac{Bit}{Byte} \cdot \frac{1}{1.024}}\quad{\frac{M\quad{Byte}}{k\quad{Byte}} \cdot \frac{\Delta\quad L_{i}}{\Delta\quad t_{W}} \cdot \frac{N}{N}}} = {{8{\frac{Bit}{Byte} \cdot \frac{L_{ges}}{T_{W}}}} = {R\quad\left\lbrack {M\quad{Bit}\text{/}s} \right\rbrack}}}}} \\\left( {{{with}\quad i} \in \left\{ {1,2,\ldots\quad,N} \right\}} \right)\end{matrix} & (9)\end{matrix}$of the received data will implicitly be taken into account. At a smalldata rate R_(i) of a received partial data quantity ΔL_(i), the visualimprovement of the displayed image between decoding steps D_(i−1) andD_(i) is small, whereas a high data rate R _(i) of the received partialdata quantity ΔL_(i) leads to a dramatic improvement ΔQ_(i) of the imagequality Q. An overload due to the limited performance capacity of thedecoding system is hereby excluded. There is a disadvantage, however, inthat the usage p of the decoding system remains constant with respect totime independently of the data rates R _(i) of the received partial dataquantities Δ_(Li)

A combination of both manners of proceeding according to version 3 leadsto usage of the decoding system that can be modified with respect totime.

The usage pi is dependent on the partial data quantity ΔL_(i) receivedin the time interval Δt _(w,i) .

Common to all three versions, however, is the fact that statistical andvisual properties of a transferred image cannot be taken into account.It may therefore occur that consecutive display steps V_(i−1) and V_(i)can lead to no discernable improvement of the image resolution R_(B,l)to the viewer.

FIG. 1 shows a typical course of image quality Q depending on thepercentage $\begin{matrix}{l:{100 \cdot \frac{1}{1.024} \cdot \frac{M\quad{Byte}}{k\quad{Byte}} \cdot {\frac{L}{L_{ges}}\quad\lbrack\%\rbrack}}} & (10)\end{matrix}$of the received data quantity L [kByte] of progressively coded imagescompressed in the JPEG 2000 format referring to the total data quantityL_(total) to be transferred. As a statistical quality metric$\begin{matrix}{Q_{1}:{100 \cdot {\left( {1 - \frac{e_{i}}{e_{0}}} \right)\quad\lbrack\%\rbrack}}} & \left( {11a} \right)\end{matrix}$for the current image resolution R_(B,i) is, in this instance, the meansquare error (MSE) $\begin{matrix}\begin{matrix}{e_{1}:={\frac{1}{\mu_{\max} \cdot v_{\max}} \cdot {\sum\limits_{\mu = 1}^{\mu_{\max}}\quad{\sum\limits_{v = 1}^{v_{\max}}\quad\left( {v_{n,{\mu\quad v}} - v_{i,{\mu\quad v}}} \right)^{2}}}}} \\\left( {{{for}\quad i} \in \left\{ {1,2,\ldots\quad,N} \right\}} \right)\end{matrix} & \left( {11b} \right)\end{matrix}$between the final version V_(n) of an image to be reconstructed whoseimage quality Q_(n) ideally corresponds to the image qualityQ_(orig):=100%  (11c)of the transferred original image V_(orig), and forms the basis of therespectively viewed version of a preview image V_(i) at lower resolutionand has been normalized to a quality range between 0% and 100%. In thiscase, V _(N,uv) designates the pixel value of the original image Vorigto be transferred for the pixel (μ,v), V_(i,uv) the pixel value of thei-th preview image V_(i) for the pixel (μ, v) and $\begin{matrix}{{e_{0} \equiv e_{\max}}:={\frac{1}{\mu_{\max} \cdot v_{\max}} \cdot {\sum\limits_{\mu = 1}^{\mu_{\max}}\quad{\sum\limits_{v = 1}^{v_{\max}}\quad V_{N,{\mu\quad v}}^{2}}}}} & \left( {11d} \right)\end{matrix}$the maximum possible error. A quality metric of 100% provides the bestavailable quality that can be achieved when the total image dataquantity L_(total) has been completely and successfully transferred. Inthis case (i=N) the mean square error e_(i) is ideally equal to zero:e_(N)=0.  (11e)An image quality of 0% exists when not image data has been transferred.In this case, (i=0) the mean square error ei achieves a maximum value ofemax.

FIG. 2 shows another diagram for displaying a typical course of thestatistical image quality Q depending on the percentage l of thereceived data quantity L of progressively coded image data compressed inthe JPEG 2000 format referring to the total data quantity L_(total) (inMByte) to be transferred. Here, in addition to the continual functioncourse Q(l), the time t_(i) of the decoding procedures D_(i) with theassociated percentage of the data quantity share Δll and image qualityvalues AQ_(i) for a statistically equal quality improvementΔQ _(i) :=h(Δl _(i))=Q _(i) −Q _(i−1)(for iε{1,2, . . . N,})  (12)of 10.00% per decoding step i has been specified, whereby bothrelationshipsQi:+Q(l_(i)) and  (12a)Qi=1:=Q(l_(i−1))  (12b)give the image quality of the preview images V_(i) and V_(i−1) . Thisshows that when there is a small portion Δll the quality increase AQ_(i)is high, i.e. the data quantity ΔLi that must be received between twoimprovement steps D_(i−1) and D_(i) is initially relatively small andincreases with the increase of the existing data quantity List(j) at thepoint in time t_(j).

As can be seen in FIG. 2, a large number N of decoding steps D_(i) for aproportionally small quantity Δll of data within the framework of thedetermination of the decoding step D_(i) described above in accordancewith version 1 leads to an overload of the decoding system.

In practice, the courses of the image quality Q illustrated in FIGS. 1and 2 result from statistically mean and normalized values of a randomquality metric. The relationship indicated above between the imagequality Q and the mean square error e is therefore understood for purelyillustrative purposes. In fact, the normalized image quality coursesQ(l) are stored in a data memory and are determined independently of thetransfer.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a technology that canbe used to optimize the downloading of progressively coded image data.

The optimization concerns, for example, the amount of time and systemresources used.

This object is achieved in accordance with the invention by a processand unit for gradual processing and, where necessary, display ofprogressively coded image data wherein the time spans Δt_(w,l) betweenthe time points t_(i−1) and t_(i) of consecutive decoding steps D_(i−1)and D _(i) , during which the necessary decoded partial data quantitiesΔL_(i) are made by the network user for the display of preview images insuccessively refined resolution R_(B), are shortened and optimized withrespect to a minimization of the total usage p of the decoding system.For this purpose, the data reception rates R_(i) used in the inventionfor transferring the individual partial data quantities ΔL_(i) take intoaccount the improvements ΔQ_(i) of the image quality Q achieved by theindividual decoding steps D_(i) and the temporary usage pi of the systemcomponents, for the determination of the decoding time point t_(i).Instead of a measurement of the data reception rate R_(i) and theachieved image quality improvements ΔQ_(i) during data transfer ensues,only a measurement of the execution times for the individual decodingsteps D_(i) are made, so as to avoid an overload of the system.

The wait times Δ_(tv,l) between the time points i−1 and t_(i) ofdirectly consecutive decoding steps D_(i−1) and D_(i) are therebycalculated in the invention by integrating statistical image qualityparametersΔ{overscore (Q)}_(v,i):=E{ΔQ_(i)}  (13)of received partial image data in such a way that the decoding stepsD_(i), which do not lead to a perceptible improvement ΔQ_(v,l) of theimage quality Q showing the degree of resolution of an image to bereconstructed, are suppressed. Mean values are thereby used as thresholdvalues for the perceptibility of a refinement of the image resolutionR_(B) that are derived from statistical experiments within the frameworkof psycho-optical measuring rows on a number of test individuals. Theconsideration of statistical quality parameters ΔQ_(v,l) of transferredimages leads, in comparison to the previously described version 3, to afurther reduction of the temporary usage pi of the decoding system.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a typical course of the image quality Qshowing the degree of resolution RB, depending on the percentage l ofthe received data quantity L of progressively coded image datacompressed in the JPEG 2000 format, referring to the total data quantityL_(total).

FIG. 2 is a further diagram of a typical course of the image quality Qdepending on the percentage l of the received data quantity L ofprogressively coded image data compressed in the JPEG 2000 format,referring to the transferred total data quantity L_(total), whereby, inaddition to the continual function course Q(l), the time point t_(i) ofthe decoding procedures D_(i) with the associated percentage of dataquantity Δl,l and image quality values ΔQ_(i) for a statistically equalquality improvement ΔQ_(i) of 10.00% per decoding step is specified,

FIG. 3 is a diagram as in FIG. 2 wherein individual decoding time pointst_(i) are suppressed to reduce the number N of decoding steps by takinginto account statistical quality parameters ΔQ _(v,l) of received imagedata.

FIG. 4 is a block diagram of a functional unit for execution of aprocess for decoding progressively decoded image data taking intoaccount statistical quality parameters ΔQ_(v,l) of received image datain accordance with a configuration example of the invention.

FIG. 5 is a flow chart to illustrate the invention process in which thewait times Δt _(v,l) between the time points t_(i−1) and t_(i) ofconsecutive decoding steps D_(i−1) and D_(i) with integration of imagequality parameters ΔQ _(v,l) of received partial image data iscalculated in such a way that decoding steps Di that do not lead to aperceptible image improvement are suppressed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention solution shall be explained in more detail in thefollowing using the configuration examples in FIG. 3 thru 5.

The inventive process for the gradual decoding, archiving and graphicdisplay of progressively coded image data is illustrated by the flowchart 500, which is reproduced in FIG. 5. After the initialization (S0)of a counter variable i for the decoding steps D_(i) with the value(l:=1) the invention makes a determination (S1) of the percentageΔl1,min of the minimum quality Ql1,min of the first minimum partial dataquantity ΔL ¹ ,min of progressively coded data to achieve a predefinedminimum quality Q1,min to be received at the beginning of the loadingprocess (S2), referring to the total data quantity L _(total) to beloaded, whereupon this image data will be loaded (S2). Then the waittime Δt _(w,1) for the loading of the first minimum partial dataquantity ΔL₁,min will be determined by measuring the time span Δt _(p,1)between the start time of the loading process (t0=0 S) and the time t1of the first decoding step D1 (S3). As long as the total data quantity L_(total) to be transferred has not been completely received then thefollowing steps will be executed in a loop:

-   -   Incrementing (S4) of the counter variables l for the individual        decoding steps Di by (l:=i+1),    -   Determination (S5) of the percentage Δl1,min of the minimum        partial data quantity ΔL1,min of progressively coded image data        to achieve a next-higher predefined minimum quality Q_(i,min),        referring to the total data quantity L_(total) be loaded.    -   Loading (S6) of further image data until this minimum partial        data quantity ΔL_(i,min) was received and a predefined reference        duration        Δt_(v,i):=(fΔt_(D,i=1)),  (14)    -    that serves as a function of the computation time Δt _(P,i−1)        determined for the preceding decoding step D_(i−1) , has        expired, and    -   Determination (S7) of the wait time Δt _(w,l) for loading the        i-th minimum partial data quantity ΔL _(i,min) through        measurement of the computation time Δt_(P,l) required for        decoding this partial data quantity ΔL_(i,min) within the time        span Δt _(w,l) between the time t_(i−l) of the immediately        preceding decoding step and the time of the current decoding        step D_(i).

FIG. 3 shows a typical course of the image quality Q depending on thepercentage l of the received data quantity L of progressively codedimage data compressed in the JPEG 2000 format, referring to the totalimage data to be transferred, referring to decoding steps D_(i) nregular, constant time intervals Δt_(w) _(—) are executed. The waittimes Δt _(V,l) between the time points t_(i−1) and t_(i) of directlyconsecutive decoding steps D_(i−l) and D_(i) are thereby calculatedusing statistical image quality parameters ΔQ_(v,l) of received partialimage data in such a way (S3, S7) that the decoding steps D_(i) that donot add any significant image improvement are suppressed.

The individual decoding steps D_(i) in the invention occur at regulartime intervals Δt _(w) of equal duration, which result from theperformance capacity and the current usage P_(i) the system components404 being used for decoding but only when the percentage Δl of theincrease ΔL_(i,min) of the data quantity, L referring to the total dataquantity L _(total), resulting from the individual decoding steps D _(i)is sufficient to ensure a predefined minimum quality ΔQ_(i,min) .

The parameters require for execution of the individual decoding stepsD_(i) encompass the set points ΔQ _(v,l) of the image qualityimprovements ΔQ _(v,l) is a percentage, each decoding step D_(i) and theassociated set-point portionsΔ{overscore (l)} _(v,l) :=g(Δ _(v,i))  (15)of the partial data quantity ΔL _(i) to be received, referring to thetotal data quantity L _(total) to be transferred and are saved in adatabase 408 a that may be configured freely.

To determine the decoding time points t_(i) in the invention the datarates R_(i) upon receiving the individual partial data quantitiesΔ_(Li), the improvements ΔQ_(i) _(—) of the image quality Q generated bythe individual decoding steps D_(i) and the temporary usage p_(i) of thesystem components 404 used for decoding are measured and evaluated.

As a set point ΔQ_(v,l) of the image quality improvements ΔQ_(v,l) as apercentage for each decoding step D_(i), statistically mean values ofthe image quality improvements ΔQ_(i) to be expected in the individualdecoding steps D_(i) are used in the invention. Correspondingly, all theset point portions Δl_(v,l) of the partial data quantity Δ L_(i) to bereceived for each decoding step D_(i), respectively referring to thetotal data quantity L _(total) to be transferred, statistically meanvalues of the increases Δll as a percentage of the partial data quantityto be expected in the individual decoding steps D_(i), respectivelyreferring to the total data quantity L _(total) to be transferred.

Using the invention process yields a number of advantages:

-   -   By suppressing decoding steps D_(i) that do not lead to        perceptible image improvements, there is a reduction in the        burden P on the decoding system 404 compared to the current        state of technology.    -   By using regular, constant decoding intervals Δt_(w,l) and the        integration of image quality parameters ΔQ_(v,l) of received        partial image data for calculating the wait time Δtv,l between        the times ti−1 and ti of directly consecutive decoding steps        D_(i−1) and D_(i), a predefined maximum burden P_(max) of the        decoding system 404 is not exceeded.    -   In addition, the calculation operations to be executed during        the individual decoding steps D_(i) are independent of the        receiving data rates R_(i), the result of which is that these        sizes do not have to be known to the decoding system 404.

Another configuration example refers to the function unit 400 shown inFIG. 4, which serves for decoding, archiving and graphic display ofprogressively coded image data through successive increase of the imageresolution R_(B) with an increase in the data quantity L of the imagedata loaded in a receiving data carrier 402 and visualized using adisplay device 404 a. In this instance, the receiving data carrier 402has a fill display 402 a, which calculates and specifies the accumulatedactual value as a percentage fist of the data quantity L ist alreadyloaded in the receiving data carrier 402, referring to the total dataquantity to be transferred L_(total). The function unit 400 ischaracterized by a decoding system 404, which decodes image data in Ndecoding steps D_(i) received depending on statistical qualityparameters ΔQ_(v,l) saved in the receiving data carrier 402.

The function unit 400 in the invention has access to a data carrier 408that contains set points of the improvement of the image quality Q as apercentage per decoding step as well as the association set pointportion of the partial data quantities Δ_(Li) to be received, referringto the total quantity L_(total), and a first threshold switch 410 whoseoutput signal A1 specifies whether a loaded partial data quantity ofimage data to be loaded between the time points t_(i−1) and t_(i) of thepreceding and current decoding steps D_(i−l) and D_(l), referring to thetotal data quantity L_(total) to be loaded is sufficient to achieve apredefined threshold value for the improvement of image quality Q.Because A1 assumes the logical value of “one”, the following must apply:$\begin{matrix}{{\Delta\quad Q_{1}}\overset{1}{\geq}{\Delta\quad{\overset{\_}{Q}}_{v,i}\quad{{bzw}.}}} & \left( {16a} \right) \\{{\Delta\quad l_{1}}\overset{1}{\geq}{\Delta\quad{\overset{\_}{l}}_{v,i}}} & \left( {16\quad b} \right)\end{matrix}$In addition, the function unit 400 includes a first time measurementunit 406, which measures the required computation time within the waittime between times t_(i−l) and t _(i) of consecutive decoding stepsD_(i−l) and D_(i) to decode a received partial data quantity through thedecoding and display system 404, which serves as an output basis forcalculating a reference time duration that is forwarded as a set pointto the second threshold switch. A second time measurement unit 414measures the actual required time duration for decoding the currentpartial data quantity through the decoding system 404 and delivers themeasured actual value to the second threshold switch 412. The functionunit 400 also has access to a second threshold switch 412 whose outputsignal A2 specifies whether a predefined wait time has passed after theprevious decoding step Di for decoding the current partial dataquantity, which results in a function of the execution time for decodingthe immediately preceding partial data quantity through the decodingsystem 404. Because A2 assumes the logical value of “one”, the followingmust apply: $\begin{matrix}{{\Delta\quad t_{1}}\overset{1}{\geq}{\Delta\quad{t_{v,i}.}}} & (17)\end{matrix}$

Using an AND-gate 416, whose Boolean input signals are formed by theoutput signals A1 and A2 of both threshold switches 410 and 412, acontrol signal S is calculated, which delivers a start signal when alogical value of “one” is encountered that causes the decoding system404 to execute a decoding step Di and also serves to start, undo orrestart both time measurement units 406 and 414.

Although modifications and changes may be suggested by those skilled inthe art, it is the intention of the inventor to embody within the patentwarranted hereon all changes and modifications as reasonably andproperly come within the scope of his contribution to the art.

1. A method for processing data comprising the steps of: graduallyprocessing progressively coded image data, for reconstructing an image,by successive increases of image resolution, in a plurality of directlyconsecutive decoding steps, thereby increasing data quantity of saidimage data loaded into a receiving data carrier; and calculatingrespective waiting times between respective points in time of saiddirectly consecutive decoding steps using statistical image qualityparameters as said image data are increasingly loaded, and suppressingdecoding steps that do not result in an perceptible/noticeableimprovement of said image resolution of said reconstructed image.
 2. Amethod as claimed in claim 1 wherein the step of determining saidwaiting times comprises (a) determining for each decoding step a datarate as said image data are loaded into said receiving data carrier, (b)determining improvement in a quality measure indicating a degree ofimage resolution achieved by the respective decoding steps and (c)determining current usage of components used for the decoding step.
 3. Amethod as claimed in claim 1 comprising the steps of: initializing acounter variable for the decoding steps by setting it to the value one;determining the percentage of a first minimum data quantity of theprogressively coded image data to be loaded in said receiving datacarrier for achieving a predetermined minimum quality at the beginningof said loading process, referenced to the total data quantity of saidimage data to be loaded into said receiving data carrier, and loadingsaid first minimum partial quantity into said receiving data carrier;determining a waiting time for loading said first minimum data quantityby measuring a time span between starting of the loading process forloading said first minimum partial data quantity and a point in time ofa first of said decoding steps; incrementing said counter variable forthe individual decoding steps by one; determining a percentage of aminimum partial data quantity of said progressively coded image data tobe loaded for achieving a next-higher predetermined minimum quality,referenced to said total data quantity, and loading data until saidminimum partial data quantity has been loaded and a predeterminedcomputation time has passed, said computation time being a function ofsaid predetermined computation time for the preceding decoding step;determining the waiting time for loading each successive minimum partialdata quantity by measuring the required computation time for loadingeach successive minimum partial data quantity from the point in timespan of an immediately preceding decoding step to the point in time of acurrent decoding step; and repeating the above steps until said totalimage data quantity has been loaded.
 4. A method as claimed in claim 3comprising conducting the respective decoding steps at regular timeintervals of identical duration if the percentage of increase of theloaded data quantity in the respective decoding steps is sufficient toensure a predetermined minimum quality of the reconstructed image,referenced to a total data quantity to be loaded.
 5. A method as claimedin claim 3 comprising storing parameters for executing the respectivedecoding steps in an arbitrarily configurable data base, includingpercentage set points for image quality improvements for each decodingstep, and associated set point portions of the partial data quantitiesto be loaded, referenced to the total data quantity.
 6. A method asclaimed in claim 5 comprising determining said parameters using astatistical measuring technique.
 7. An apparatus for processingprogressively coded image data by successive increases in imageresolution of an image reconstructed from the image data therebyincreasing data quantity of said image data being loaded into areceiving data carrier, said apparatus comprising: said receiving datacarrier having a fill display for calculating and indicating an currentaccumulated percentage of said data quantity already loaded into saidreceiving data carrier; and a decoding system for decoding said imagedata loaded into the receiving data carrier, in a plurality of directlyconsecutive decoding steps, dependent, for each decoding step, onstatistical quality parameters of the image data loaded into thereceiving data carrier.
 8. An apparatus as claimed in claim 7 comprisesa data carrier contains set points for improvements in image quality ofsaid reconstructed image as a percentage, for each decoding step, andassociated set portions of partial data quantities to be received bysaid receiving data carrier.